Влад137,
<input type="button" name="button" id="button_pdt" value="Товары" onclick="change()"/>
<input class="tab_pdt" id="tab1" type="radio" name="tabs" checked>
<input class="tab_pdt" id="tab2" type="radio" name="tabs">
<input class="tab_pdt" id="tab3" type="radio" name="tabs">
<input class="tab_pdt" id="tab4" type="radio" name="tabs">
<input class="tab_pdt" id="tab5" type="radio" name="tabs">
<style>input{display:block;}</style>
<script>
var active = 0, inputs=document.querySelectorAll('.tab_pdt');
function change(){
active= ++active % inputs.length;
inputs[active].checked = true
}
</script>